Indonesia’s navy said on Monday it fired shots at a Chinese trawler when it refused to stop fishing in Indonesian waters, and then seized the vessel and its eight crewmembers.

An Indonesian frigate intercepted the trawler on Friday near the Natuna islands in Indonesia’s exclusive economic zone, which overlaps with the southernmost reaches of the South China Sea, said navy western fleet command spokesman Major Budi Amin.

Amin said the frigate fired shots which hit the stern of the fishing vessel, Gui Bei Yu-27088, after it ignored repeated warnings to stop. He said no one was injured.

“This arrest was made to show the world that Indonesia will take firm action against ships that violate our territory,” Amin said. He said Indonesia followed standard international procedures in dealing with foreign ships entering its territory, including providing warnings with flags, voices and warning shots.

This arrest was made to show the world that Indonesia will take firm action against ships that violate our territory

Indonesian Navy Major Budi Amin

China claims most of the South China Sea.

Tensions between the two countries flared in March when Indonesia intercepted a Chinese fishing vessel off the Natuna islands. A Chinese coast guard vessel collided with the trawler as it was being towed, allowing it to escape.

Indonesia, the world’s largest archipelago nation, has taken a tough stance against illegal fishing since President Joko “Jokowi” Widodo took office in 2014.